iAs Concentrations Research Articles

Differential metabolism of inorganic arsenic in mice from genetically diverse Collaborative Cross strains.

Mice have been frequently used to study the adverse effects of inorganic arsenic (iAs) exposure in laboratory settings. Like humans, mice metabolize iAs to monomethyl-As (MAs) and dimethyl-As (DMAs) metabolites. However, mice metabolize iAs more efficiently than humans, which may explain why some of the effects of iAs reported in humans have been difficult to reproduce in mice. In the present study, we searched for mouse strains in which iAs metabolism resembles that in humans. We examined iAs metabolism in male mice from 12 genetically diverse Collaborative Cross (CC) strains that were exposed to arsenite in drinking water (0.1 or 50ppm) for 2weeks. Concentrations of iAs and its metabolites were measured in urine and livers. Significant differences in total As concentration and in proportions of total As represented by iAs, MAs, and DMAs were observed between the strains. These differences were more pronounced in livers, particularly in mice exposed to 50ppm iAs. In livers, large variations among the strains were found in percentage of iAs (15-48%), MAs (11-29%), and DMAs (29-66%). In contrast, DMAs represented 96-99% of total As in urine in all strains regardless of exposure. Notably, the percentages of As species in urine did not correlate with total As concentration in liver, suggesting that the urinary profiles were not representative of the internal exposure. In livers of mice exposed to 50ppm, but not to 0.1ppm iAs, As3mt expression correlated with percent of iAs and DMAs. No correlations were found between As3mt expression and the proportions of As species in urine regardless of exposure level. Although we did not find yet a CC strain in which proportions of As species in urine would match those reported in humans (typically 10-30% iAs, 10-20% MAs, 60-70% DMAs), CC strains characterized by low %DMAs in livers after exposure to 50ppm iAs (suggesting inefficient iAs methylation) could be better models for studies aiming to reproduce effects of iAs described in humans.

Arsanilic acid contributes more to total arsenic than roxarsone in chicken meat from Chinese markets

Organoarsenicals have been used in poultry production for years, however, studies focused on roxarsone (ROX), with little attention to p-arsanilic acid (ASA). We assessed arsenic (As) concentration and speciation in chicken meat collected from 10 cities in China. The geometric mean for total As in 249 paired raw and cooked samples was 4.85 and 7.27 μg kg–1 fw, respectively. Among 81 paired raw and cooked samples, ASA and ROX were detected in >90% samples, suggesting the prevalence of organoarsenical use in China. ASA contributed the most (45% on average) to total As in cooked samples, followed by As(V), DMA, As(III), and ROX (7.2–22%). ASA was found to contribute more to total As in chicken meat compared to ROX for the first time. Arsenic in chicken meat showed considerable geographic variation, with higher inorganic arsenic (iAs) being detected from cities with higher ROX and ASA, indicating that organoarsenical use increased iAs concentration in chicken meat. When health risk was estimated, dietary exposure to iAs would result in an increase of 3.2 bladder and lung cancer cases per 100,000 adults. The result supports the removal of organoarsenicals in poultry production from Chinese market and further supports its removal from the global markets.

Arsenite and its trivalent methylated metabolites inhibit glucose-stimulated calcium influx and insulin secretion in murine pancreatic islets.

Chronic exposure to inorganic arsenic (iAs), a common drinking water and food contaminant, has been associated with an increased risk of type 2 diabetes in population studies worldwide. Several mechanisms underlying the diabetogenic effects of iAs have been proposed through laboratory investigations. We have previously shown that exposure to arsenite (iAs(III)) or its methylated trivalent metabolites, methylarsonite (MAs(III)) and dimethylarsinite (DMAs(III)), inhibits glucose-stimulated insulin secretion (GSIS) in pancreatic islets, without significant effects on insulin expression or insulin content. The goal of the present study was to determine if iAs(III) and/or its metabolites inhibit Ca2+ influx, an essential mechanism that regulates the release of insulin from β cells in response to glucose. We found that in vitro exposures for 48h to non-cytotoxic concentrations of iAs(III), MAs(III), and DMAs(III) impaired Ca2+ influx in isolated murine pancreatic islets stimulated with glucose. MAs(III) and DMAs(III) were more potent inhibitors of Ca2+ influx than iAs(III). These arsenicals also inhibited Ca2+ influx and GSIS in islets treated with depolarizing levels of potassium chloride in the absence of glucose. Treatment with Bay K8644, a Cav1.2 channel agonist, did not restore insulin secretion in arsenical-exposed islets. Tolbutamide, a KATP channel blocker, prevented inhibition of insulin secretion in MAs(III)- and DMAs(III)-exposed islets, but only marginallyin islets exposed to iAs(III). Our findings suggest that iAs(III), MAs(III), and DMAs(III) inhibit glucose-stimulated Ca2+ influx in pancreatic islets, possibly by interfering with KATP and/or Cav1.2 channel function. Notably, the mechanisms underlying inhibition of GSIS by iAs(III) may differ from those of its trivalent methylated metabolites.

Vortex-assisted supramolecular solvent microextraction based on solidification of floating drop for preconcentration and speciation of inorganic arsenic species in water samples by molybdenum blue method

A new vortex-assisted supramolecular solvent microextraction based on solidification of floating drop (VA-SSM-SFD) has been developed for preconsentration and spectrophotometric determination of inorganic arsenic (iAs) species in various water samples. The method is based on the formation of arsenomolybdenium blue complex followed by VA-SSM-SFD procedure and subsequent spectrophotometric determination in a microcell. The supramolecular solvents consisted of reverse micelles of 1-dodecanol in tetrahydrofuran (THF) which were formed by in-situ coacervation of 1-dodecanol micelles in aqueous samples. Under optimized conditions, iAs (V) formed hetroploy blue complex and was directly determined. The concentration of iAs (III) was determined by subtracting iAs (III) from the total iAs following the oxidation of iAs (III) to iAs (V) by permanganate in acidic medium. Under optimal conditions, the calibration curve for iAs determination showed good linearity in the range of 5.0–140.0 μg L−1(R2 = 0.9988) and detection limit was found to be 0.4 μg L−1, which is much lower than WHO guideline of 10 μg L−1 for iAs in drinking water. The repeatability and reproducibility for 20 μg L−1 were found to be 2.47 and 3.9%, respectively. The proposed method was successfully applied to speciation of iAs species in real water samples.

Market Basket Survey of Arsenic Species in the Top Ten Most Consumed Seafoods in the United States.

The study focused on the determination of arsenic species in the top ten most consumed seafoods in the United States. Fifty-four samples were collected from local supermarkets, and their species identities were confirmed by DNA barcoding. The total arsenic in the samples varied greatly in the range of 8-22200 ng/g (wet mass). Speciation analysis based on extraction of water-soluble and nonpolar arsenic showed that inorganic arsenic (iAs) was found only in clams and crabs, while arsenobetaine (AsB) predominates in most samples. Among the other arsenicals, trimethylarsoniopropionate (TMAP) was found in most matrices with higher concentrations in crabs, and arsenosugars existed in most clams and crabs. Nonpolar arsenic accounted for 1-46% of the total arsenic in the samples. The accuracy of the analytical results was evaluated using standard reference materials and spike recovery tests. The survey showed that the iAs concentrations in America's most consumed seafood products are much lower than the tolerable intake set by the Joint FAO/WHO Expert Committee, even at the highest levels found in this study.

Titania-doped zirconia as platinum group metal support in catalysts for treatment of combustion engine exhausts streams

Edible seaweeds with a relatively high total arsenic concentration have been a global concern. As the largest seaweed producer, China contributes about 60 % of the global seaweed production. The present study investigated 20 seaweed species collected from representative seaweed farming sites in the six provinces along the Chinese coastline, of which Saccharina japonica, Undaria pinnatifida, Neopyropia spp., Gracilaria spp., Sargassum fusiforme were listed as the most consumed seaweeds in Food and Agriculture Organization of the United Nations (FAO). The inorganic arsenic (iAs) concentration in most of the seaweeds was below maximum limits (0.3 mg iAs/kg) as seaweed additives for infant food in the National Food Safety Standard of Pollutants in China (GB2762-2017, 2017), except for the species Sargassum, in which the iAs concentration significantly exceeded the limit and ranged from 15.1 to 83.7 mg/kg. Arsenic speciation in 4 cultivated seaweeds grown in both temperate and subtropical zones is reported for the first time. No significant differences in total As and iAs concentration were identified, except slightly higher total As concentration were found in Saccharina japonica growing in the temperate zone. The estimated daily intake (EDI) of toxic iAs via seaweed consumption was generally below the EFSA CONTAM Panel benchmark dose lower confidence limit (0.3 μg/kg bw/day) except for all Sargassum species where the EDI was significantly higher than 0.3 μg/kg bw/day. Moreover, the first-ever reported data on As speciation indicated very high iAs concentrations in Sargassum hemiphyllum and Sargassum henslowianum. To minimize the food chain iAs exposure, reducing both human intake of Sargassum spp. and the used of Sargassum spp. for animal feed is highly recommended.This study showed that edible seaweed Sargassum spp. consumption may pose a health risk related to inorganic arsenic (iAs) exposure. The risk of iAs exposure via seaweed consumption or livestock is a concern that needs to be monitored. The arsenic accumulation and speciation may be predominantly species-dependent rather than environmental-dependent.

Long-Term Combinatorial Exposure to Trichloroethylene and Inorganic Arsenic in Genetically Heterogeneous Mice Results in Renal Tubular Damage and Cancer-Associated Molecular Changes.

Trichloroethylene (TCE) and inorganic arsenic (iAs) are environmental contaminants that can target the kidney. Chronic exposure to TCE is associated with increased incidence of renal cell carcinoma, while co-exposure to TCE and iAs likely occurs in exposed human populations, such as those near Superfund sites. In order to better understand the kidney health consequences of TCE and/or iAs exposure, a genetically heterogeneous mouse population derived from FVB/NJ and CAST/EiJ mouse strains and deficient for multidrug resistance genes (Abcb1atm1Bor, Abcb1btm1Bor) was chronically exposed for 52-weeks to varying concentrations of TCE and iAs. Although no exposure group resulted in primary renal cell tumors, kidneys from exposed mice did have significant increases in histologic and biochemical evidence of renal tubular disease with each toxicant alone and with combined exposure, with males having significantly higher levels of damage. Although no added increase in tubular disease was observed with combination exposure compared to single toxicants, molecular changes in kidneys from mice that had the combined exposure were similar to those previous observed in an embryonic stem cell assay for the P81S TCE-induced renal cell carcinoma mutation in the Von Hippel-Lindau syndrome (VHL) gene. While this model more accurately reflects human exposure conditions, development of primary renal tumors observed in humans following chronic TCE exposure was not reproduced even after inclusion of genetic heterogeneity and co-carcinogenic iAs.

A rapid on-line non-chromatographic hydride generation atomic fluorescence spectrometry technique for speciation of inorganic arsenic in drinking water

A rapid on-line non-chromatographic hydride generation atomic fluorescence spectrometry is described and determination of inorganic arsenic (iAs (III) and iAs (V)) species is achieved within a single run. Thioglycolic acid (TGA) was used for on-line pre-reduction of iAs (V) and quantification of arsenic species was accomplished via calibration with one As form; as iAs (III). Samples and calibration standards were prepared in Tris buffer (pH:7.2) for selective hydride generation and without on-line pre-reduction, iAs (V) signal was negligible up to 150 ng ml−1. The limit of detection (LOD) values for iAs (III) and iAs (V) were 27 pg ml−1 and 36 pg ml−1, respectively. Recovery studies were performed, certified reference material (TMDA-61) was used to test the accuracy of the method and the results were in good agreement. iAs (V) was the main form in all water samples whereas iAs (III) concentration was <LOD value for some samples.

Factors Affecting Transfer of the Heavy Metals Arsenic, Lead, and Cadmium from Diatomaceous-Earth Filter Aids to Alcoholic Beverages during Laboratory-Scale Filtration.

Filtration methods for alcoholic fermented beverages often use filter aids such as diatomaceous earth (DE), which may contain elevated amounts of the heavy metals arsenic (As), lead (Pb), and cadmium (Cd). Here, we evaluated factors affecting transfer of these heavy metals from DE to beer and wine. A laboratory-scale filtration system was used to process unfiltered ale, lager, red wine, and white wine with three types of food-grade DE. Filtrate and DE were analyzed for heavy metals using ICP-MS, in addition to LC-ICP-MS for As-speciation analysis. Use of 2 g/L DE containing 5.4 mg/kg soluble inorganic As (iAs) for filtering beer and wine resulted in significant ( p < 0.05) increases of 11.2-13.7 μg/L iAs in the filtered beverage. There was a significant ( p < 0.05) effect from the DE quantity used in filtration on the transfer of iAs in all beverage types, whereas no alterations were observed for Pb and Cd levels. Methods to wash DE using water, citric acid, or EDTA all significantly ( p < 0.05) reduced iAs concentrations, whereas only EDTA significantly reduced Pb levels. Cd concentrations were not affected by any wash method. These data indicate that specific steps can be taken to limit heavy-metal transfer from DE filter aids to beer and wine.

State of the science review of the health effects of inorganic arsenic: Perspectives for future research.

Human exposure to inorganic arsenic (iAs) is a global health issue. Although there is strong evidence for iAs-induced toxicity at higher levels of exposure, many epidemiological studies evaluating its effects at low exposure levels have reported mixed results. We comprehensively reviewed the literature and evaluated the scientific knowledge on human exposure to arsenic, mechanisms of action, systemic and carcinogenic effects, risk characterization, and regulatory guidelines. We identified areas where additional research is needed. These priority areas include: (1) further development of animal models of iAs carcinogenicity to identify molecular events involved in iAs carcinogenicity; (2) characterization of underlying mechanisms of iAs toxicity; (3) assessment of gender-specific susceptibilities and other factors that modulate arsenic metabolism; (4) sufficiently powered epidemiological studies to ascertain relationship between iAs exposure and reproductive/developmental effects; (5) evaluation of genetic/epigenetic determinants of iAs effects in children; and (6) epidemiological studies of people chronically exposed to low iAs concentrations.

Validation and inter-laboratory study of selective hydride generation for fast screening of inorganic arsenic in seafood

It is advisable to monitor and regulate inorganic arsenic (iAs) in food and feedstuff. This work describes an update and validation of a method of selective hydride generation (HG) with inductively coupled plasma mass spectrometry (ICP-MS) for high-throughput screening of iAs content in seafood samples after microwave-assisted extraction with diluted nitric acid and hydrogen peroxide. High concentration of HCl (8 M) for HG along with hydrogen peroxide in samples of a same concentration as used for extraction leads to a selective conversion of iAs to volatile arsine that is released and transported to the detector. A minor contribution from methylarsonate (≈20% to iAs) was found, while HG from dimethylarsinate, trimethylarsine oxide is substantially suppressed (less than 1% to iAs). Methodology was applied to Certified Reference Materials (CRMs) TORT-3, DORM-3, DORM-4, DOLT-4, DOLT-5, PRON-1, SQID-1 and ERM-CE278k, in some of them iAs has been determined for the first time, and to various seaweed samples from a local store. The results were always compared with a reference method and selectivity of iAs determination was evaluated. An inter-laboratory reproducibility was tested by comparative analyses of six fish and four seaweed samples in three European laboratories, with good agreement of the results. The method of HG-ICP-MS is sensitive (limit of detection 2 μg kg−1 iAs), well suited for screening of large number of samples and selective at iAs concentration levels at which maximum limits are expected to be set into EU legislation for marine samples.

Concentrations and health risks of inorganic arsenic and methylmercury in shellfish from typical coastal cities in China: A simultaneous analytical method study.

Shellfish consumption is an important pathway for coastal residents exposure to inorganic arsenic (iAs) and methylmercury (MeHg). An integrated method had been developed for simultaneous determination of iAs and MeHg in shellfish with microwave-assisted extraction and high performance liquid chromatography-inductively coupled plasma mass spectrometry identification. The limits of detection were 0.0520, 0.1003 and 0.0015 mg/kg (dry weight) for AsIII, AsV and MeHg, respectively. The proposed method was applied to evaluate the contents and health risks of iAs and MeHg in shellfish from the typical coastal cities (Lianyungang and Yantai) in China. The concentrations of iAs and MeHg in fresh shellfish were 0.10-1.69 mg/kg and 0.46-6.38 μg/kg, respectively. The target hazard quotient and target cancer risk values of iAs were the highest for the children and adults in Lianyungang, and were respectively larger than 1 and 1 × 10-4, indicating both non-carcinogenic and carcinogenic risks of iAs exposure were significant in this area.

Bioaccumulation and acute toxicity of As(III) and As(V) in Nile tilapia (Oreochromis niloticus)

The distribution of arsenic in the different tissues of tilapia fish is determined by the exposure time and the depuration rate. The mechanisms of toxicity/carcinogenicity depend on the arsenic species involved in the biotransformation processes. After a 7-day exposure period, the accumulation of inorganic arsenic (iAs) in the tilapia tissues studied was in the order: liver > stomach > gills > muscles. In bioaccumulation assays, the values of the organ uptake constant (ka) ranged from 0.06 to 0.51 mL g−1 d−1, while the depuration rate constant (kd) values were in the range 0.03–1.15 d−1. Higher iAs bioaccumulation factor (BCF) values were observed for the stomach (3.1 mL g−1) and the liver (1.6 mL g−1), reflecting their high capacity to accumulate iAs species. These organs act as long-term storage sites for iAs, following chronic exposure. The LC50 values were determined considering the average iAs concentration and the cumulative fish mortality. For As(III), the LC50 values indicated fish mortality at concentrations above 30 mg L−1. The fish showed greater tolerance to exposure to As(V), compared to As(III), with fish mortality after the second day of exposure requiring an As(V) concentration 7-fold higher than As(III).

A Comprehensive Review of Arsenic Exposure and Risk from Rice and a Risk Assessment among a Cohort of Adolescents in Kunming, China

Inorganic arsenic (iAs) is carcinogenic and highly concentrated in rice. Dietary exposure to iAs is concerning among adolescents due to their developmental stage and iAs’s long-latency effects. This paper aimed to assess iAs exposure from rice and related lifetime cancer risks (LCR) among adolescents in Kunming, China. A comprehensive literature review of iAs levels in rice and LCR in humans was also conducted. Average daily consumption of rice (ADC) was estimated from 267 adolescents (15–18 years). Rice samples obtained from 6 markets were analyzed for iAs concentration (AC). Estimated daily intake (EDI) of iAs was calculated using ADC, AC, and average body weight (BW). Lifetime Cancer Risk (LCR) was calculated using EDI and U.S. EPA derived iAs oral slope factor. The AC was 0.058 mg/kg and the average BW and ADC were 67.5 kg and 410 g/day for males and 55.5 kg and 337 g/day for females. The EDI and LCR were 3.52 × 10−4 mg/kg-BW/day and 5.28 × 10−4 for both males and females, with LCR 5 times above the U.S. LCR upper limit of 1.0 × 10−4. While the AC was below the Chinese maximum contaminant level of 0.2 mg/kg, study results indicated that Kunming adolescents may be at increased risk for iAs-related cancers.

Peripubertal Urinary Arsenic Concentrations and Subsequent Insulin Resistance among Russian Boys

Introduction: Inorganic arsenic (iAs) has been associated with type 2 diabetes in adults, but there are few studies in children. We assessed the associations of peripubertal urinary iAs concentrations with insulin resistance (IR) at adolescence among boys in Chapaevsk, Russia.Methods: 516 8-9 year-old boys were enrolled from 2003-2005 in a prospective cohort study of environmental exposures, growth and puberty. At study entry, parents/guardians completed medical history and demographic questionnaires, and speciated urine As concentrations (µg/L) were measured with ion chromatography coupled to ICP-MS; LOD&amp;#61;0.5, except arsenate (AsV) &amp;#61;1.0. Follow-up included annual physical exams and biennial collection of fasting blood samples. At ages 10-13 years, 430 boys had IR calculated by the homeostatic model. &amp;#931;iAs was calculated as the sum of arsenite (AsIII) &amp;#43; AsV, and levels were categorized as low (&amp;lt;1.0), medium (1.0-2.0), or high (&amp;gt;2.0). AsIII and AsV were also dichotomized as high vs. low (&amp;#8805; vs. &amp;lt; LOD). Total As (tAs), calculated as &amp;#931;iAs &amp;#43; monomethylarsonic acid &amp;#43; dimethylarsenic acid, was categorized by quartiles. Associations of As species with IR were examined by multivariable generalized estimating equations for repeated measures, adjusted for urine specific gravity, age, and BMI.Results: 9.1% of boys had IR. The medians (max) of tAs, AsIII, AsV, and &amp;#931;iAs were 5.9 (254), 0.4 (57), 0.2 (15.7) and 0.7 (62) µg/L, respectively. In multivariable models, compared to low &amp;#931;iAs, the OR (95% CI) associated with medium and high &amp;#931;iAs were 1.90 (0.85, 4.28) and 2.42 (0.90, 6.52), p-trend&amp;#61;0.06. Of the iAs species, only AsV was associated with significantly increased odds of IR, with OR&amp;#61;2.75 (95% CI: 1.17, 6.47). tAs was not associated with IR.Conclusion: In this Russian cohort, higher peripubertal iAs was associated with increased odds of IR over four years of follow-up.Funded by EPA R82943701, NIEHS ES014370, ES000002 &amp; ES024907.

Application of the adverse outcome pathway (AOP) approach to inform mode of action (MOA): A case study with inorganic arsenic

ABSTRACTThe aim of this study was to establish a process for deriving a chemical-specific mode of action (MOA) from chemical-agnostic adverse outcome pathway (AOPs), using inorganic arsenic (iAs) as a case study. The AOP developed for this case study are related to disruption of cellular signaling by chemicals that strongly bind to vicinal dithiols in cellular proteins, leading to disruption of inflammatory and oxidative stress signaling along with inhibition of the DNA damage responses. The proposed MOA for iAs incorporates this AOP, overlaid on a background of increasing oxidative stress and/or co-exposure to mutagenic chemicals or radiation. The most challenging aspect of developing a MOA from AOP is the incorporation of metabolism and dose-response, neither of which may be considered in the development of an AOP. The cellular responses to relatively low concentrations (below 100 parts per billion) of iAs in drinking water appear to be secondary to binding of trivalent arsenite and its trivalent metabolite, monomethyl arsenous acid to key cellular vicinal dithiols in target tissues, resulting in a co-carcinogenic MOA. The proposed AOP may also be applied to non-cancer endpoints, enabling an integrated approach to conducting a risk assessment for iAs.

Selective and fast screening method for inorganic arsenic in seaweed using hydride generation inductively coupled plasma mass spectrometry (HG-ICPMS)

A method for the determination of inorganic arsenic (iAs) without chromatography using hydride generation — inductively coupled plasma mass spectrometry (HG-ICPMS) is applied to 40 brown macroalgae samples (Fucus vesiculosus, Ascophyllum nodosum, Saccharina latissima). Determining iAs in seaweed matrices is a challenge and, in this study, using 2% HNO3 and 3% H2O2 extraction media the HG-ICPMS outperformed the most commonly used method of HPLC-ICPMS for the determination of iAs in the seaweed samples. There was a good comparison between the simple and fast HG-ICPMS and the more accurate but time-consuming HPLC-HG-ICPMS. Linear regression showed reasonable linearity (R2 of 0.82), with a slope slightly higher than 1 (1.15 ± 0.09) and intercept 0.03 ± 0.01 when comparing the concentrations of iAs determined with the two methods. Hence there is a minor overestimation of iAs with HG compared to the HPLC-HG, however, the method is well suited as a quick screening method. The iAs concentration was below 1% of total arsenic concentration for all the seaweed samples irrespective of using HG-ICPMS or HPLC-HG-ICPMS.

Metal Biomonitoring and Comparative Assessment in Urine of Workers in Lead-Zinc and Steel-Iron Mining and Smelting.

The exposure of heavy metals (lead (Pb), cadmium (Cd), copper (Cu), nickel (Ni), and metalloid arsenicals) and their effects on workers' health from a lead-zinc mine (145 workers) and a steel smelting plant (162 workers) was investigated. Information on subject characteristics was obtained through a questionnaire. We determined the urinary levels of Pb, Cd, Cu, Ni, and arsenicals (including inorganic arsenic (iAs), monomethylarsonic acid (MMA), and dimethylarsinic acid (DMA), as were 8-hydroxydeoxyguanosine (8-OHdG) and cystatin C. Lead-zinc mine foundry workers had significantly higher concentrations of urinary Pb, Cd, Cu, Ni, iAs, and MMA than did steel smelting plant workers. Individuals who had consumed seafood in the previous 3days had higher concentrations of urinary Ni than did individuals who had not consumed seafood. The urinary Cd concentrations in the two groups of factory workers may have been affected by daily smoking. There was no significant difference in urinary 8-OHdG between workers from the lead-zinc mine foundry and the steel smelting plant. Urinary Pb and Cd had significant positive linear dose-dependent effects on 8-OHdG. Urinary cystatin C, a sensitive biological indicator reflecting early renal damage, was found at higher levels in lead-zinc mine workers than in steel smelting plant workers. Binary logistic regression analysis showed that age and urinary Cd were significantly associated with urinary cystatin C. These results indicated that workers from lead-zinc mines may be exposed to higher levels of heavy metals which could lead to greater risk of kidney damage.

Inorganic arsenic exposure increased expression of Fas and Bax gene in vivo and vitro

Accumulating evidences have shown that apoptosis plays an important role in mediating the therapeutic effects and toxicity of arsenic. Fas and Bax genes are critical regulatory genes for apoptosis. In this study, we investigated the association between levels of Fas and Bax expression and the three arsenic species (inorganic arsenic (iAs), monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA)) in vivo and vitro. Three arsenic species in urine were measured and levels of Fas and Bax expression were examined by the quantitative real-time PCR (qPCR) for all subjects. We found that Fas and Bax mRNA expression in the exposed group were significantly higher than that in the control group. The levels of gene expression were positively correlated with the concentrations of urinary iAs, MMA and DMA in all subjects. Sodium arsenite induced Fas and Bax mRNA expression, then MMA and DMA did not induce mRNA expression in MDA-MB-231 and XWLC-05 cells. The findings of the present study indicated that iAs, MMA, and DMA had different effects on expression of Bax and Fas gene.

Comparison of on-site field measured inorganic arsenic in rice with laboratory measurements using a field deployable method: Method validation

A commercial arsenic field kit designed to measure inorganic arsenic (iAs) in water was modified into a field deployable method (FDM) to measure iAs in rice. While the method has been validated to give precise and accurate results in the laboratory, its on-site field performance has not been evaluated. This study was designed to test the method on-site in Malawi in order to evaluate its accuracy and precision in determination of iAs on-site by comparing with a validated reference method and giving original data on inorganic arsenic in Malawian rice and rice-based products. The method was validated by using the established laboratory-based HPLC-ICPMS. Statistical tests indicated there were no significant differences between on-site and laboratory iAs measurements determined using the FDM (p = 0.263, ά = 0.05) and between on-site measurements and measurements determined using HPLC-ICP-MS (p = 0.299, ά = 0.05). This method allows quick (within 1 h) and efficient screening of rice containing iAs concentrations on-site.